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    <meta charset="UTF-8">
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    <title>Document</title>
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<script>
    var year = Number(prompt("请输入一个年份"))
    if (year%4==0 && year%100!=0 || year%400==0){
        console.log('是闰年')
    }else{
        console.log('不是闰年')
    }
</script>
</html>